| A | B |
|---|
| anaerobic exercise | exercise in which the demand for oxygen exceeds the supply of oxygen |
| endorphins | natural painkillers |
| isokinetic | anaerobic exercise that involves the use of special machines |
| warm-up | period of mild exercise that gradually increases heart rate |
| aerobic exercise | exercise that imporves the cardiovascular and respiratory systems |
| cool-down | a period after vigorous exercise during which the heartbeat is allowed to return to its resting state slowly |
| rapid eye movement | your eyes flicker back and forth behind your closed eyelids |
| myoclonic jerk | during sleep you experience a sudden jerk of your muscles |
| insomnia | difficulty in falling asleep or staying asleep |
| isotonic | contracting and relaxation of muscles through the full range of motion |
| isometric | muscle contract but does not shorten |
| target heart rate | heart you need to maintain during exercise |
| REM | sleep during which your eyes flicker back and forth behind your closed eyelids |
| NREM | sleep in which your eyes are relaxed |
